Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study: Methods and findings to date

Abstract

Purpose-To describe baseline and longitudinal findings of the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study.Methods-The CLEK Study is an eight-year, multi-center, natural history study of 1,209 patients with keratoconus who were examined annually for eight years. Its goals are to prospectively characterize changes in vision, corneal curvature, corneal status, and vision-specific quality of life.Results-CLEK Study subjects had a mean age at baseline of 39.3 +/− 10.9 years. At study entry, 65% of the patients wore rigid contact lenses, and 14% reported a family history of the disease. Subjects exhibited a seven-year decrease in high-(2.03 letters) and low-(4.06 letters) contrast, best-corrected visual acuity, with 19% demonstrating decreases of 10 or more letters in high-contrast, best-corrected acuity and 31% of subjects demonstrating decreases of 10 or more letters in low-contrast, best-corrected acuity in at least one eye. Subjects exhibited an average eight-year increase in corneal curvature of 1.60 D in the flat corneal meridian, with 24% demonstrating increases of 3.00 D or more. The eight-year incidence of corneal scarring was 20%, with younger age, corneal staining, steeper baseline corneal curvature, contact lens wear, and poorer low-contrast visual acuity predictive of corneal scarring. Data from the National Eye Institute Visual Function Questionnaire suggest that the effect of keratoconus on vision-specific quality of life is disproportionate to its low prevalence and clinical severity.Conclusion-Although we report measures of disease severity and visual function across the CLEK sample, clinicians can begin to envisage the course of keratoconus in individual patients by determining whether factors predictive of disease progression are present in those patients.

Penetrating Keratoplasty for Keratoconus : Visual and Graft Survival Outcomes

“…However, de Lavalette et al (17) reported a female predominance of 65% in their study. Various studies have reported that keratoconus has an equal prevalence in both genders, (1,18) a greater prevalence in males, (14)(15)(16)19) and a greater prevalence in females. (20) One possible reason for the increased relative frequency of male subjects undergoing transplantation compared with female subjects is an increased tendency for males to receive surgical treatment so as to improve occupational performance.…”

Effects and adverse events after CXL for keratoconus are independent of age: a 1-year follow-up study

“…Despite the reduced rate of progression of KC with increasing age, KC can progress in older patients, resulting in reduced visual acuity and quality of life. 1,[6][7][8] Whether iatrogenic CXL in older adults with naturally cross-linked corneas has the same positive effect as in younger adults is unknown. A recent study on the safety of CXL found that age Z35 years was a major risk factor for adverse events after CXL.…”

“…1 Corneal cross-linking (CXL) using riboflavin and ultraviolet-A light has been shown to effectively increase corneal stiffness and even to reduce ectasia. [2][3][4] These findings originate from studies done mainly in young adults and led to the widespread use of CXL to stabilize KC in this group of patients, who have a 20% risk of progressing to a stage that requires therapeutic keratoplasty.…”

Keratoconus und dessen Behandlung mit Hornhautvernetzung und Kontaktlinsen: ein Überblick

“…Bei unilateralem KC kann sich auch am sog. guten Auge (Auge mit forme fruste KC) in einem Teil der Fälle ein progredienter KC entwickeln [9], es kann jedoch auch stabil bleiben [10]. [19] in Verbindung mit der Spaltlampe eine Hornhauttopographie und Ultraschallpachymetrie an.…”